1. Technical Field
The technical field relates to a loudspeaker magnetic circuit used in various audio and video apparatuses, including vehicle-mounted applications, and to a loudspeaker.
2. Background Art
FIG. 18 is a sectional view of a conventional outer magnet type magnetic circuit used in a loudspeaker. The conventional magnetic circuit 3 shown in FIG. 18 is an outer magnet type, and includes magnet 1, first plate 2A, and yoke 2B. Both first plate 2A and yoke 2B are formed of magnetic substance.
Yoke 2B includes a bottom part, and a projection (so-called center pole) disposed on the center of the bottom part. Magnet 1 is provided in the center thereof with through-hole 1A. Magnet 1 is mounted on the bottom part of yoke 2B in such a manner that the center pole of yoke 2B penetrates through through-hole 1A.
On the other hand, first plate 2A is placed on the upper surface of magnet 1. With this configuration, magnetic gap 4 is formed between first plate 2A and the center pole of yoke 2B.
As magnet 1 used in such a conventional loudspeaker, a rare-earth magnet having an extremely high magnetic property is used.